This invention relates to heat exchanger tubes and more particularly to heat flux limiting sleeves for heat exchanger tubes.
Steam generators utilized with Liquid Metal Fast Breeder Reactors (LMFBR) and designed to produce dry saturated steam will see severe temperature differences between the hot sodium on the shell side and the saturated water within the tubes. Normally with the heat exchanger, the greater the temperature differential, the greater the effectiveness of the heat exchanger elements. However, there appears to an upper limit above which high heat transfer rates can cause tube damage due to chemical concentrations and rapid temperature fluctuations, particularly at the boiling surfaces. The combination of liquid metal on the shell side and nucleate boiling within the tubes results in extremely high heat fluxes. When prestressed double wall tubes are utilized in LMFBR steam generators, the temperature differential across the double wall tubes may be sufficient to produce separation at the interface of the walls. Thus, to protect single and double wall tubes a heat flux limiter is required.